This is where the two pairs of lines round the north and south sides of the sidings are connected together. I couldn't find a name for it but it's still a junction.

I've changed it to amenity=beer_garden

amenity=*

specifically says

"Biergarten or beer garden is an open-air area where alcoholic beverages along with food is prepared and served. See also the description of the tags amenity=pub;bar;restaurant. A biergarten can commonly be found attached to a beer hall, pub, bar, or restaurant. In this case, you can use biergarten=yes additional to amenity=pub;bar;restaurant.

None of this really helps as the important thing about the Beer Garden is availabilit of alcoholic beverages, which the leisure=outdoor_seating
outdoor_seating=garden combination doesn't imply.

I propose the Biergaten tag be changed to encompass the English Beer Gardens instead.

What's the correct tag for a beer garden?

Not really - but there's always a nagging doubt I've forgotten something - area=yes tags when converting linea featurs to polygons were my last omissiion somebody picked up on...

I think I have the connections between lines correct but I expect the physical locations will need tweaking when some better photography is available. Platform 2 needs to become a shape rather than a line.

What is the correct tag for Common Lane?

Not sure what the jargon means, sorry. It's a railway station.

I'm not sure, sorry.

It was attached to node/4290859478 which I merged with 5784212748. I just copied the tags across.

The tag is actual railway:ref:DB.

Not sure - it was park of one of the nodes that I merged. The CRS is SHF.

Sorry got caught out by the bug so I missed the the area tag.